Commutator



Se t. 11, 1923.

c, A. ADAMS COMMUTATOR' Original File'd Aug. 19.

1916 4 Sheets-Sheet 1 INVENTOR m/M z 4; 14

H15 ATTORNEYS.

Sept. 11, 1923. 1,467,467

(3. A. ADAMS COMMUTATOR Original Filed Aug. 19. 1916 4-Sheets-Sheet 2 71/5 A TTOR/VE Y5.

Sept. -II, 1923.

q. A. ADAMS GOMMUTATOR Original Filed Aug; 19,

1916 4 Sheets-Sheet 5 M mi g a v g E M q M m R M W m J 5 w. Q Q b m J y WW aa L7 Q M lllllll v M F ,nm. x mm M ,7 a C MU w W m w 3 ww Q\ kw mm Q R \x fi Sept. 11, 1923. 1,467,467

C. A, ADAMS I COMMUTATOR Original Filed Aug. 19 1916 4 Sheets-She's}. 4

m N im 4 7%. A a/la 1 By M, %M MM M HIS ATTORNEYS Patented Sept. 11, 1923.

UNITED STATES- 1,467,467 PATENT oFFic I COMFORT A. ADAMS? or CAMBRIDGE, MASSACHUSETTS, ASS G L E FRANCIS s. MARDEN, or NORFOLK, CONNECTICUT. f r

COMMUTATOR.

Application filed August 19, 1916, Serial No. 115,768l. Renewed January 25, 1923.

To all whom it may concern:

Be it known that I, COMFORT A. ADAMS, a citizen of the United States; and resident of Cambridge. in the county of hiiddlesex, State of Massachusetts, have invented certain new and useful Improvements in Commutators; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to circuit controlling means for electric hammers or similar tools. The invention is directed more par ticularly to the provision ofmeans for energizing the operating coils of the hammer at predetermined time lntervals and to a suitable degree, the coils being alternately energized and deenergized so that theplunger or reciprocating element of the hammer may be made to strikea succession of rapid blows on the tool or its carrier.

It is an object of the invention to provide a commutator by which the coils of the hammer will be alternately energized and deenergized without opening their circuits. This result is attained by establishing a shunt circuit first about one coil and then about the other so that only one coil is at any time completely energized. The arrangement is such that comparatively heavy currents maybe used and the inductanceof each coil may be utilized in turn to help build up the magnetic field of the other coil.

Another object of the invention'is to con trol the strength of the hammerblows by controlling the energizing current as by a rheostat in the supply circuit. The fre-i quency of the blows may also be controlled by a rheostat which controls thespeed of the motor that drives the commutator.

The invention also provides a commutator of inexpensive, simple and compact construction which may be easily carried about out regard to polarities thereby rendering it unnecessaryfor the operator to-have any considerable knowledge of the electrical arrangement. I y

The invention also embraces numerous The construction 1 other features and advantages which will,

Fig. 2 is a plan view of the apparatus :65

with the cover portion removed; Fig. 3 is a view in section taken along the line 3-3 of Fig. .1;

Fig. l is a plan section through the com mutator along the line t-4: of Fig. 1

Fig. 5 is a view showing, partlyin section, the shaft of the apparatus and one of the slip rings with its corresponding brushsupa porting binding post; and

Fig. is a simplified diagram of the cir cuit connections of the commutator and a hammer associated therewith. p i y Referring to the drawings inwhich similar reference characters denote similar parts throughout the several views-thereof, l0is a base made preferably of aluminum and formed with a chamber within which cer- I tain parts of the apparatus may be mounte ed The base is provided with'a removable bottom plate 11.. To the topo'f the base is attached in any convenient manner a motor 12 for driving the commutator. The

bearing 1.3:at the outer end of the motor is provi'declwith a rod l t; .A similar rod 15 is attached to the top ofthe base at the 1 other end of the apparatus. These. rods serve to hold in placethe cover 16 which is provided with apertures through which the rods extend. Clamping nuts 17 retain the cover in place. The wholeapparatus may thenbeconveniently carriedby means of the handle 18. The cover 16 may be provided with ventilation holes 19 as desired. The shatt of the. motor is extendedas at 20 to a ball bearing 21 on a supporting columnQQ attached. tothe other end of the base 10. A. ventilating fan'23 may be mounted on the shaft 20 between the motor and the commutator.

The commutator comprises an. insulating disk 24 fastened to .theshaft 20 and. carrying upon its periphery a pair of. conductingv segments 25 and 26: separated from each other at points 4 0. On either sideof the diskand segments are smaller insulating disks 27 and 28 fastened to the shaft 20.

Each of these disks 27 and 28 is surrounded by a collector or slip ring 29 and 30 respectively. The conducting segment 25 is connected to slip ring 29 by a connector bar 31, (Fig. 4). A similar connector bar 32 completes the circuit between conducting segment 26 and slip ring 30. Beside the disk carrying the segments 25 and 26 is a brush holder comprising a frame 33 having a bearing portion 34 through which passes a shaft 35 supported in brackets 36 attached to but insulated from the base 10. Springs 37 wound about the shaft and fastened at one end to the brackets 36 and at the other ends to the frame 33 maintain the brush against the surface of the segments of the commutator. The frame 33 is provided with a cross-bar 38 upon which a brush 39, preferably of carbon, is supported. As shown most clearly in Fig. 3, the brush 39 is narrower than the gaps 40 between the conducting segments 25 and 26. To prevent the brush from dropping into the gaps as they pass by the brush insulating bridges 4L1. and 42 are provided at the ends of the gaps. The bridges are made narrow to reduce friction between them and the brush. Instead of being made of insulating material they may be made of metal with insulating strips between their ends and the ends of the conducting segments. While the arrangement illustrated is the preferred one, the bridges may be omitted and the brush holder may be provided with an insulating spacing block which, with the brush itself, will be of sufiicient width to bridge the gaps and thus prevent the brush from dropping into the latter. The brush is clamped in place by a screw 43 which also retains the spacing block if one is used. Undercertain conditions a brush formed of a conducting member wide enough to bridge the gaps lOmay be substiin the drawing. Vhile the brush holder is insulated from the base, provision is made for connecting to the holder a wire which forms part of the circuit connections of the apparatus. This may be accomplished in anv well known manner.

Two binding posts 442 and 45, each insulated from the base, are adapted to be connected to wires passing through the top of the base. Each of these binding posts is formed with an eye at the top for the pur pose of retaining brushes 46 and 47 in place by means of screws 48 and 49, the brushes being formed with flexible extensions adapted to engage the slip rings 29 and 30 respectively.

Within the chamber in the base of the apparatus may be mounted a quick break and non-arcing switch for controlling the supply circuit. This switch is designated 51 in the wiring diagram, Fig. 6, and its operating handle is shown at 52 in Fig. 2. Within the chamber in the base is also mounted a rheostat 53 for controlling the current supplied to the armature 54: of the motor. Instead of controlling the motor through its armature it may be controlled through its field in the usual manner. This rheostat may be of any desired construction and is provided on the outside of the base with an operating button and a dial 56 which has an indicating mark traveling adjacent to a fixed scale 57 graduated according to the degrees of speed attainable by the motor. As shown in Fig. 6 the field 58 of the motor con nected directly across the supply conductors. A fixed resistance 60 is also mounted within the chamber in the base and in series with this fixed resistance is a rheostat 61 for varying the strength of the hammer blows. This rheostat 61 may be of any desired construction and is operated by a button 62 upon the outside of the base. Like the rheostat of the motor it is provided with an indicating dial 63 and a scale 64 graduated to represent various intensities of the hammer blow. The base may be provided with any desired number of ventilating apertures 65. Almost all of the wiring of the apparatus is contained within the chamber in the base. For the purpose of connecting supply leads to the apparatus the base is provided with a pair of sockets 66 which may conveniently be mounted in an insulating plate set in an aperture at one end of the base.

A corresponding arrangement of three sockets 67 at the other end of the base provides for the connection of the hammer leads to the apparatus.

Referring particularly to the wiring diagram of Fig, 6, main conductors 68 and 69 within the base are connected to the terminals of the sockets 66. 68 leads directly to one terminal of the fixed resistance 66 while 69 leads to one terminal of the switch 51. From the other terminal of the switch a con-- ductor 70 leads to one of the end sockets 67. The field 58 of the motor and its armature 54k and controlling rhcostat 53 are mounted in parallel between conductors 68 and 70. A conductor 71 connects the other end socket 67 to the rheostat 61 which is connected in series with the fixed resistance 60 and the conductor 68. The middle socket of the group 67 is connected by wire 7 2 to the brush holder frame 33, this wire passing through the base of the apparatus and being connected to this frame in any convenient manner, as previously referred to. The binding post 45 is connected to conductor 70 by wire 73 while the binding post 4A: is connected to the conductor 71 by a wire 74:.

The hammer shown diagrannnatically in Fig. 6 may be of any construction. It comprises a strikingcoil 75 and a lifting coil 7 6 from the outer ends of which conductors lead to plugs adapted to fit into the sockets 1 tion of the striking' plunger. g i commutator is moved in the direction of the '67. The common or mid connection of the coils is connected to one terminal 77 of a switch, the other terminal 78 of which is connected to a lead running toa plug which engages the middle one of the sockets 67. The switch is controlled by an operating handle 7 9 mounted near the handle 80 of the 51 is closed and the motor speed adjusted to the proper degree by a manipulation of plugs and sockets are connected, it being only necessary for the operator to make sure that the middle plug is in the: middle socket Assuming that the commutator is in the position shown, in which the brush '39 is in con' tact with neither of the conducting segments 25 or 26, then both ofthe coils75, 7 6 of the hammer will be connected in series across the supply means and as they are opposing each other in theirefli'ect there will be no'mo- It now the arrow of Fig. 6 so that the brush 39 engages conducting segment 26, a. short circuit or shunt will beestablislied about the coil 75 of the hammer but the coil 76 will he energized by current which passes over conductor 68 through the resistance 60, rheostat 61, conductor 71 and hammerlead, coil 7 6, switch 77 8, the central hammer lead, conductor 72. brush 39, segment 26. slip ring 30, brush 47, binding post 45, conductor 73', switch 51' and conductor 69 to the other supplylead. Coil 76 will thus be energized to lift the striking plunger and hold it so longas current continues toflow through the coil. At the instant the conducting segment 26 leaves the brush 39' the return path through the conductor 72 will be broken and the self-induction of the coil 6 will cause a discharge i'rom the latterback'through the line. Sinccthe circuit is o 'aenat the brush 39 the inductive discharge or kick of coil 76 will iass through coil 75. This discharge will he in such a direction through 75 aswill tend to produce polarity like that which will be produced when, an instant later, the brush 39 makes contact .Wltli the segment 25 of the commutator establishlng a short circuit or shunt about the coil 76 and cans- 1 ing coil 7:) tobe energized over the ,foll0w- '6 ing path: conductor 68, resistance 60, rheo stat 6 1, conductor 74', brush 46, slip ring 29, segment 25, brush 39,wire T2, middle hammer lead, switch 77%78, coil 7 5, outer hammer lead back to wire 70, switch wire 69 to the supply lead. I Current will at this instant be flowing through coil in the same direction as the inductive discharge t'rom the coil 76 and will persist as longas the brush 39is in contact with segment 25. At the instant the brush passes off of thissegment the coil 75 will discharge or ki'ck through the coil 76' and the polarity produced by this inducti 'e current will he thesame as that produced by the main current in this same coil when at the next instant the coil 75 is short circuited'. These operations will be repeated so long as the apparatus is in operation. The inductance of each coil is as above explained, used to help build up the current in the other coil so that instead of wasting all of the electro-kinetic energy of the current in one coil in heat and delivering a new supply to the other coil, a part of this energy is transferred directly to the second coil with an accompanying increase in therate' of decrease of current in the first coil and in the rate or" increase of current in the latter coil. This isan important feature of the invention as it means an increase in the aggregate energyfdelivered to the plunger during each stroke, particularly for high speeds of the commutator.

Bya proper timing of the interval at which each coil is's'hort circuite'd, apparatus can be adjusted so that the short circuit is established about the coil 76 at sub stantially the instant that the striking plunger begins to rebound from the impact member 82 at the handle end of the hammer. The eiiect of the coil 75 will at this instant become apprecialf'ileand and" to attract the striking plunger just as it is moving in the same direction on the rebound. This is a further advantage of the present. construction as it renders a maximum effect to the blow upon the tool. The proper timing of the apparatus is efl'ected by means of the controlling rheostat As the energizing circuits have. been traced above, it will be seen that the rheostat 61 is always present in the energizing cir cult of each coil so that it has the same effect on the degree-of energization of each coil. It therefore is immaterial which way the hammer leads are connected to the sockets 67 so long as the middle plug is in the middle socket.

\Vhile the resistance 60 has been referredv to as a fixed resistance it will. be understood that throughout the majority of operations of the apparatus this resistance will be of a predetermined magnitude, but of course may he changed from time to time, or even entirely" eliminated if desired. The function of this resistance is to prevent a &

dead short circuit between the line conduc tors if for any reason, due to some abnormal condition, the are or spark between the brush 39 and the commutator segments 25 and 26 should be drawn completely across the gap between these segments, in which case the line would be short circuited by an arc of very low resistance. The fixed resistance is therefore inserted as an extra safeguard, although it has been found in practice that the apparatus may be properly operated without any such resistance in circuit. The resistance is also helpful. as its presence reduces the time constant of the circuit including the hammer coils and hence reduces the time required for the current to build up in these coils. Instead of using a narrow brush 39 as illustrated, it is possible to operate the apparatus by using a brush of a width that will bridge the gap between the segments of the commutator. In this case the inductive kick of each, coil as the brush. passes from one segment to the other will take place through the brush and the two segments in parallel instead of through the other coil. Vihile the apparatus operates successfully under these conditions the arrangement first described is preferred.

Various modifications or changes in the details of construction of my invention may be made without departing from the principle thereof.

I claim:

1. A system of the character described, comprising a source of current, a pair of coils connected together, main conductors connecting the coils in series with the source, a magnetizable plunger within the coils, a common conductor leading from the point of connection of the coils, a contact member to which the common conductor is connected, a pair of movable conductim members adapted to engage the contact member alternately, a pair of movable conducting incur bers, each electrically connected to one of the firstnamed conducting members, a fixed contact member engaging each of the last named movable contact members, and conductors connecting the last-named fixed contact members to the main conductors.

2. A system of the character described, comprising a source of current, a pair of coils connected together, main conductors connecting the coils in series with the source, a magnetizable plunger within the coils, a common conductor leading from the point of connection of the coils, a fixed contact member to which the common conductor is connected, a pair of rotary arcuate conducting members adapted to engage the fixed Contact member alternately, insulating members between the ends of the arcuate conductingmembers, said insulating members being wider than the fixed contact 7 member, so that the latter is out of engagenaent with the arcuate members for an appreciable interval of time during the rota tion of these members, a pair of circular conducting members adapted to rotate with the arcuate conducting members, and each electrically connected to one of said arcuate members, a fixed contact member engaging each of the circular conducting members, and conductors connecting the last'named fixed contact members to the main conductors.

3. A system of the character described, comprising a source of current, a pair of coils connected together, main conductors connecting the coils in series with the source, a magnetizable plunger within the coils, a

common conductor leading from the point of connection of the coils, a fixed contact member connected to each of the main conductors, movable contact members adapted to engage each of the fixed contact members, a pair of movable contact members, each electrically connected to one of the first named movable contact members, insulat ing members between. the ends of the pair of movable contact members, a fixed contact member connected to the common conductor and adapted to be engaged successively by the pair of movable contact members to establish a short-circuit about each of the coils alternately, said last-named fixed contact member being of lesser width than the insulating members, so that an interval of time occurs between the establishment of each short-circuit to permit inductive discharge of the non-short-circuit coil. through the other coil.

i. The combination with an electric hammer having a pair of windings operating on a inagnetizable plunger, of a circuit controller therefor for permiting the energizetion of said windings alternately, said controller comprising a pair of conducting segments, a brush common to both said windings engaging said segments alternately. a pair of collector rings each having electric connection with one of said segments, a brush for each collector ring, a supply cir euit for energizing said windings, one conductor of said circuit being connected to one winding, the other to the other winding, connections between. the brush of one collector ring and. one conductor and from the brush of the other collector ring to the other conductor, means for rotating the segments and collector rings, and means for controlling the speed of said rotating means.

5. A system of the character described, comprising a pair of coils, a magnetizable plunger adapted to be reciprocated by a cur rent in said coils, an impact member against which said plunger-strikes when attracted by one of said coils, means for establishing a short circuit about each of said coils alternately in order to permit the other coil to attract said plunger, and means for controlling saidshort circuiting means to cause the same to establish the short circuit about the coil which attracts said plunger against said impact member at the instant when said plunger rebounds from said member.

6; A system of the character described, comprising a striking coil and a lifting coil, a magnetizable plunger adapted to be reciprocated by said coils, an impact member against which said plunger strikes when attracted by said lifting coil, a source of current connected to said coils, means for establishing a short circuit about said striking coil in order that said plunger may be attracted by said lifting coil and for thereafter establishing a short circuit about said lifting coil at the instant when said plunger rebounds from said impact member in order that said striking coil may then be effective to attract said plunger.

7. The method of operating an electric tool having a striking coil, a lifting coil, a magnetizable plunger adapted to be reciprocated by the coils, and a member to take up the impact of the plunger When attracted by the lifting coil, Which consists in supplying continuous electric current to the terminals of the coils, establishing a short circuit about the striking coil for a predetermined period of time, breaking the shortcircuit about the striking coil to permit the inductive discharge of the lifting coil to discharge through the striking coil, establishing a short-circuit about the lifting coil While the discharge from the lifting coil has an appreciable value and While the plunger is rebounding from the impact member. and maintaining the short-circuit about the lifting coil for a predetermined period to permit the striking coil to attract the plunger.

In testimony whereof I ailix my signature.

COMFORT A. ADAMS. 

